The present invention relates to an electric battery capacity and usage system, and more particularly, to a battery capacity/usage system particularly useful in electric powered boats.
Electric powered boats, like many other electric powered vehicles, require an electric power system, which typically includes one or more onboard rechargeable storage batteries. It is important to monitor the capacity of the batteries in real time to avoid an unexpected or unwanted loss of power resulting in a shutdown of the electric motor during operation. Safety and convenience concerns dictate the importance of having a battery “fuel gage,” so that boat occupants are not stranded, or unable to maneuver away from danger.
Prior art electric powered boat technology, a volt meter is typically employed to monitor the residual voltage supply of the batteries. The voltmeter indicates the remaining charge on the batteries based upon voltage alone without time indication. Alternatively, a current measuring type meter may be employed to monitor the battery capacity. In the current measuring type meter, wiring must be interrupted by shunts, and Peukert's Equation is used to estimate the remaining time.
The information supplied to a boat operator when using a voltmeter indicator may be unreliable. For example, when using a 36V battery, the battery is only effective to drive the electric motor within the voltage range of about 32V to about 36V. Under this circumstance, it is possible that an operator may have insufficient battery power to pull the boat in shore when the meter shows that the battery is low, but not empty. In this regard, many prior art and configurations can only measure the remaining time under a full load condition. In such a configuration, the exact remaining time for using the battery when the boat is driven in a slower speed cannot be ascertained.
Also, the prior art metering systems for determining battery charge are costly and difficult to install. In addition, the wire leading to the battery requires the placement of an intervening shunt resister exposing metal components to the elements. Exposed metal is subject to corrosive forces, particularly in a sea environment. Also, a different voltmeter is required for different types of batteries.
Therefore, it would be desirable to provide a universal battery capacity monitor for use in electric boats that can provide a true reading of the time remaining before loss of power and motor shutdown. Furthermore, it would be desirable to provide battery monitor that is easy to install, and which will be more resistant to corrosive forces encountered in boating environments.